Method of hiding areas on a disc like recording of the optically rewritable type

ABSTRACT

A next generation of high speed CD-RW discs for high speed recording (4×-10×) need a new write strategy, which is not suited for recording at lower speeds (1×-4×). Existing CD-RW recorders may accept these discs and make recordings according to existing write strategies. This will result in unreadable discs. To prevent this, a Power Calibration Area (PCA) and a Program Memory Area (PMA), both needed for recording, are hidden for the existing recorders. As a result the disc will be rejected. In a method wherein an absolute time reference (ATIP) is applied on the disc, the start locations of said areas being determined by a fixed time offset relative to a subsequent Lead-in area, an embodiment of the invention is obtained by making the PCA and PMA untraceable by introducing and Absolute Time in Pre-Groove (ATIP) time code jump of for instance one minute just before the Start time of the Lead-in area. Another embodiment is obtained by introducing the absolute Time in Pre-Groove (ATIP) time code jumps between a Test Area and a Count Area of the program calibration area (PCA).

[0001] The invention relates to a method of preventing recording on adisc like recording medium of the optically rewritable type, the methodcomprising applying a pre-groove on the disc like recording mediumadapted to write data therein in accordance with a first write strategy,reserving a program calibration area (PCA) for optimum power control(OPC) and/or a program memory area (PMA) for temporarily storing a tableof content (TOC) on said disc like recording medium.

[0002] The invention further relates to a recording apparatus adaptedfor recording digital information signals on a disc like recordingmedium of the optically rewritable type, said apparatus comprising inputmeans for receiving digital information signals, encoding means forcoding the received digital information signals for recording on thedisc like recording medium, writing means for writing opticallydetectable marks representing the encoded information signals on thedisc like recording medium in accordance with a first write strategy,address determining means for locating on the disc like recording mediuma program calibration area (PCA) to be used for a optimum power control(OPC) procedure and/or a program memory area (PMA) to be used fortemporarily storing a table of content (TOC).

[0003] The invention also relates to a disc like recording medium of theoptically rewritable type according to the preamble of claim 6.

[0004] A disc like recording medium of the optically type is disclosedfor instance in European Patent 390 268 (PHN13148), which isincorporated by reference herein. Such a disc which allows recordingapart from playback may be referred to as a CD-Recordable (CD-R), aCD-Erasable (CD-E) or a CD-Rewritable (CD-RW).

[0005] As the name implies, CD-RW is a media and recording system thatallows the user to erase previously recorded information and then torecord new information in its place, making short-term storage feasibleon CD media. This is accomplished by means of a new CD-RW media using“phase change” technology that allows a recording laser beam to changethe media material from amorphic to crystalline by means of a shift inpower.

[0006] The first generation of CD-RW discs are designed for speedapplications covering a range of 1 times-4 times the nominal speed of aconventional CD-ROM disc, being approximately 150 kbs. The nextgeneration CD-RW discs however will designed for high speed applicationsranging from 4 times-10 times this nominal speed. Because of the typicalbehavior of phase change materials, these discs need a new writestrategy, which is not suited for recording at lower speeds.Furthermore, the existing write strategies defined for 1×, 2× and4×recording speed, do not work on these new discs.

[0007] Some of the existing CD-RW recorders, designated to operate withthe lower speed ranges, are recognizing the new high speed discs andreject them. But others will accept these discs and make recordings onthem according to one of the existing write strategies, for instancedefault at 2× speed. These recordings will result in unreadable signals,thereby destroying previously recorded information.

[0008] In consequence, amongst other things, it is an object of theinvention to obviate the above-mentioned disadvantages. According to oneof its aspects a method according to the invention is characterized bymaking one or both of said areas untraceable for recording devicesadapted to write data on a disc like recording medium in accordance witha second, different write strategy.

[0009] As both areas are needed by a recorder, hiding these areas forexisting recorders, designed to operate with low speeds, will result inrejecting of the disc.

[0010] With a method comprising applying absolute time reference (ATIP)information in the pre-groove on the disc like recording medium, startlocations of said areas are being determined by a fixed time offsetrelative to a subsequent Lead-in area, an advantageous embodimentthereof is characterized by introducing an ATIP time code jump to ATIPtime codes before the start of the Lead-in area. The Pre Groove of aCD-RW disc contains an Absolute Time Reference in the Pre Groove. As thelocations of the PCA and PMA areas are determined by a fixed offsetrelative to the Start time of the Lead-in areas, these areas are madeuntraceable.

[0011] Further advantageous embodiments of a method according to theinvention are disclosed in the description, as well as embodiments of adisc like recording medium and recording apparatus according to theinvention.

[0012] These and further aspects and advantages of the invention will bediscussed in more detail hereinafter with reference to the disclosure ofpreferred embodiments, and in particular with reference to the appendedFigures that show:

[0013]FIG. 1 an existing ATIP versus disc diameter;

[0014]FIG. 2 a modified ATIP versus disc diameter, modified according toa first embodiment of the invention,

[0015]FIG. 3 the detailed organization of the PCA, PMA and Lead-in areaof FIG. 2, modified according to a second embodiment of the invention,

[0016]FIG. 4 a modified ATIP versus disc diameter, modified according toa third, preferred embodiment of the invention, and

[0017]FIG. 5 a recording apparatus according to an embodiment of theinvention.

[0018] In a CD-RW there are two areas preceding the Lead-in area thatare reserved for use by the recorder. The Power Calibration Area (PCA)meant for making test recordings to determine the optimal write powerfor the actual disc. Every time a disc is inserted into a CD-R drive,the laser is fired at the surface of the PCA to judge the optimum powersetting for burning the CD. Various things can influence this optimumsetting—the recording speed, humidity, ambient temperature and the typeof disc being used. The Program Memory Area (PMA) is meant to store atemporary Table of Content (TOC). A TOC contains track numbers and theirstart and stop times (for music), or sector address for the start ofdata files on a data CD.

[0019] The Information Area, the area of the disc which contains data,is divided into three areas: The Lead-in area contains digital silencein the main channel plus the Table of Contents (TOC) in the subcodeQ-channel. It allows the laser pickup head to follow the pits andsynchronize to the audio or computer data before the start of theprogram area. The Program Area contains up to about 76 minutes of datadivided into 99 tracks maximum. The Lead-out area contains digitalsilence or zero data. This defines the end of the CD program area.

[0020] Both PCA and PMA areas are needed by the recorder, so that ifthey can be hidden from existing recorders for low application speeds,these recorders cannot perform an Optimum Power Control (OPC) procedureand can not read the temporary TOC. As a result these recorders willreject the disc.

[0021] The locations of the PCA and PMA areas are determined by a fixedtime offset relative to the Starttime of the Lead-in area, asillustrated in FIG. 1

[0022] On the new generation of high speed discs, the PCA and PMA couldbe made untraceable, according to a first embodiment of the invention,for existing drives by introducing an ATIP time code jump of forinstance 1 minute just before the Starttime of the Lead-in area. Inother words: all ATIP time codes up to the Starttime of the Lead-in areaare reduced by one minute, as illustrated in FIG. 2

[0023] Existing drives cannot distinguish between old and new discs andtherefore will search for an ATIP time code (t3-00:35:65) or(t3-00:13:25) to find the PCA respectively the PMA, which they find onold discs, but never find on new discs. As a result they will reject thedisc.

[0024] New drives or upgraded drives adapted to operate with high speeddiscs at higher speed applications, can recognize the new discs and knowabout the existence of the ATIP time code jump and will search for(t3-01:00:00-00:35:65) or (t3-01:00:00-00:13:25) to find the PCA,respectively the PMA on new discs.

[0025] However, because some recorders are using the PMA also for accessduring play-back, an advantageous second embodiment leaves the PMAuntouched. In order to achieve this the ATIP Time Code jump is chosen asillustrated with reference to FIG. 3. To have some buffer area beforethe PMA, which might be useful for good access control, the time codejump could possibly be better located just after the last used frame ofthe count area in the PCA as illustrated in FIG. 3. Herein TSL=t3=StartTIME Lead-in.

[0026]FIG. 4 shows a preferred third embodiment according to theinvention. As shown in FIG. 4, the power calibration area PCA is dividedinto two areas. A first area is a Test Area, in which tests can beperformed to obtain correct reading power for a disc. A second area is aCount Area, where can be read which part of the Test Area can be used.Both areas of the PCA are divided into partitions, which must be used insequential order, starting from partition number one. The PCA can beused many times: once all partitions have been used, the total PCA mustbe erased, after which it is available for the next sequence of powercalibration procedures. The ATIP jump location is, with respect to theembodiments shown in FIG. 2 and FIG. 3, shifted into the buffer areabetween the PCA Test Area and the PCA Count Area. This results in adistance between the ATIP jump and the PMA area of 2 minutes. This givesthe advantage of more space for drives to access the PMA. As some drivesmay employ the Program Memory Area (PMA), the available free space orbuffer area may be insufficient for the use as explained with referenceto FIG. 2 and FIG. 3. It is noted that drives expect PCA Test partitionsfrom 96:51:30 to 97:11:29.

[0027] Next an embodiment of a recording apparatus according to theinvention will be described, with reference to FIG. 5. The recordingapparatus 1 comprises recording medium receiving means 2 for receiving aremovable recording medium 3. The recording medium 3 may be a disc ofthe optically rewritable type such as CD-RW, DVD-RAM or DVD-RW. Therecording medium 3 is rotationally driven by rotation means 4. Anoptical pick-up unit 5, movable in a radial direction of the recordingmedium 3, writes optically detectable marks along a spiral track 8 onthe recording medium 3 employing a light beam 6. To this purpose therecording medium 3 is provided with a suitable phase change materialwhich has different optical properties in crystalline or amorphousstates. Heating with the light beam 6 may induce these states. The lightbeam 6 is modulated by recording means 9 according to digitalinformation signals to be recorded. These digital information signalshave been suitable encoded with encoding means 10, employing EFMmodulation and CIRC error encoding, as prescribed by the CD-standards.Input means 11, which may comprise A/D conversion means and/or specialinterface circuitry, may receive analog and/or digital informationsignals.

[0028] Alternatively, recorded digital information signals on therecording medium 3, may be read via the same optical pick-up unit 5, bysuitable reading means 13. These are connected to decoding means 14 toperform EFM decoding and CIRC error correction processing. The decodedand corrected signals are outputted, via outputting means 15, which maycomprise D/A means and/or suitable interface circuitry, digital and/oranalog information signals.

[0029] In addition, address finding means 12 are provided to determineaddress information present on the recording medium 3. Such addressinformation, for example in the form of absolute time codes, may berecorded in the track 8 by means of a pre-formed track modulation asdisclosed in European Patent 390 268 (PHN 13148). Such a track isdescribed in more detail in the Dutch Patent Application NL-A-8800152(PHN 123999). The address finding means 12 derives an address signalfrom the signal components in the detection signals which are caused bythe pref-formed track modulation. The address signal is supplied to thecontrolling unit 16.

[0030] All units are controlled by the controlling unit 16. Thecontrolling unit 16 may comprise a processing unit which operatesaccording to a specific program loaded in memory means, in order toperform the method according to the invention.

[0031] Specifically the controlling unit 16 comprises informationrelating to the time jump in the Absolute Time Reference (ATIP) as maybe present in the recording medium 3, as described before. This enablesthe recording apparatus 1 to locate the previous mentioned areas on arecording medium 3 to be used for an Optimum Power Control (OPC)procedure and/or recording of a temporary table of content (TOC).

[0032] Although the invention has been described with reference to apreferred embodiment thereof, it is to be understood that these are notlimitative example. Thus, various modifications thereof may becomeapparent to those skilled in the art, without departing from the scopeof the invention, as defined by the claims. The invention may beimplemented by means of both hardware and software, and that several“means” may be represented by the same item of hardware. Further, theinvention lies in each and every novel feature or combination offeatures. It is also remarked that the word “comprising” does notexclude the presence of other elements or steps than those listed in aclaim. Any reference signs do not limit the scope of the claims.

1. A method of preventing recording on a disc like recording medium ofthe optically rewritable type, the method comprising applying apre-groove on a disc like recording medium adapted to record datatherein in accordance with a first write strategy, reserving a programcalibration area (PCA) for optimum power control (OPC) and/or a programmemory area (PMA) for temporarily storing a table of content (TOC) onsaid disc like recording medium, the method further characterized by,making one or both of said areas untraceable for recording devicesadapted to write data on a disc like recording medium in accordance witha second, different write strategy.
 2. Method according to claim 1,comprising applying absolute time reference (ATIP) information in thepre-groove on the disc like recording medium, start locations of bothareas are being determined by a fixed time offset relative to asubsequent Lead-in area, characterized by, introducing an ATIP time codejump to ATIP time codes before the start of the Lead-in area.
 3. Methodaccording to claim 2, characterized by, reducing all ATIP time codes upto the start time of the Lead-in area by approximately one minute. 4.Method according to claim 2, comprising dividing the program calibrationarea (PCA) in a program calibration Test Area and a program calibrationCount area, characterized by introducing an ATIP time code jump betweenthe program calibration Test Area and the program calibration CountArea.
 5. Method according to claim 2, characterized by, reducing allATIP time codes up to the last used area in the PCA.
 6. Disc likerecording medium of the optically rewritable type, the recording mediumprovided with: a pre-groove adapted to record data therein in accordancewith a first write strategy, a Program Calibration Area (PCA) adapted tobe used in a Optimum Power Control (OPC) procedure and/or, a ProgramMemory Area (PMA) adapted to temporarily store a table of content (TOC),characterized in that, at least one of said areas is untraceable forrecording devices adapted to record data on the disc like recordingmedium in accordance with a second, different write strategy.
 7. Disclike recording medium according to claim 6, comprising time codesrepresenting Absolute Time Reference Information (ATIP), in thepre-groove wherein a start location of at least one of said areas isdetermined by a fixed time offset relative to a subsequent Lead-in area,characterized in that, the time codes before the start of the Lead-inarea comprise a time jump of the Absolute Time Reference (ATIP).
 8. Disclike recording medium according to claim 7, characterized in that, altime codes up to approximately the start time of the Lead-in areacomprise a reduction of the Absolute Time Reference (ATIP) byapproximately one minute.
 9. Disc like recording medium according toclaim 7, wherein the Program Calibration Area (PCA) is divided in aProgram Calibration Test Area and a Program Calibration Count Area,characterized in that, the time codes between the Program CalibrationTest Area and the Program Calibration Count Area comprise a time jump ofthe Absolute Time Reference (ATIP).
 10. Disc like recording mediumaccording to claim 7, characterized in that, all time codes up to a lastused Rearea in the Program Calibration Area have a reduced Absolute TimeReference (ATIP).
 11. Disc like recording medium according to claim 7,characterized in that, the disc like recording medium is a CD-RW. 12.Recording apparatus adapted for recording digital information signals ona disc like recording medium of the optically rewritable type,comprising: input means for receiving digital information signals,encoding means for encoding the received digital information signals forrecording on the disc like recording medium, writing means for writingoptically detectable marks representing the encoded information signalson the disc like recording medium in accordance with at a least a firstwrite strategy, address determining means for locating on the disc likerecording medium a Program Calibration Area (PCA) to be used for aOptimum Power Control (OPC) procedure and/or a Program Memory Area (PMA)to be used to temporarily store a table of content (TOC), characterizedin that, the address determining means are adapted to locate at leastone of said areas of a disc like recording medium where said at leastone area is untraceable for recording apparatuses adapted to record dataon the disc like recording medium in accordance with a second, differentwrite strategy.
 13. Recording apparatus according to claim 12, whereinthe address determining means are adapted to read a time code recordedin a pre-groove on a disc like recording medium representing AbsoluteAddress Information (ATIP) wherein a start location of at least one ofsaid areas is determined by a fixed time offset relative to a subsequentLead-in area on said disc like recording medium, characterized in that,the address determining means comprise information related to a timejump in the time codes of the Absolute Time Reference before the startof the Lead-in area.
 14. Recording apparatus according to claim 13,characterized in that, the address determining means compriseinformation related to a reduction of the Absolute Time Reference (ATIP)in all time codes up to approximately the start time of the Lead-inarea.
 15. Recording apparatus according to claim 13, characterized inthat, the address determining means comprise information related to atime code jump of the Absolute Time Reference (ATIP) in the time codesbetween a Program Calibration Test Area and a Program Calibration CountArea in the Program Calibration Area (PCA).
 16. Recording apparatusaccording to claim 13, characterized in that, the address determiningmeans comprise information related to all time codes up to a last usedarea in the Program Calibration area having a reduced Absolute TimeReference (ATIP)
 17. Recording apparatus according to claim 13,characterized in that, the recording apparatus is adapted to handle aCD-RW as a disc like recording medium.